12-10GTN 725/750 Pilot’s Guide 190-01007-03 Rev. CForewordGettingStartedAudio &Xpdr CtrlCom/NavFPLDirect-ToProcChartsWpt InfoMapTrafflcTerrainWeatherNearestServices/MusicUtilitiesSystemMessagesSymbolsAppendixIndex2. Repeated touches to the NEXRAD key will toggle betweenthe Off, US, and Canada selections.Figure 12-9 NEXRAD Weather Legend12.1.5.1 ReflectivityReflectivity is the amount of transmitted power returned to the radar receiver.Colors on the NEXRAD display directly correlate to the level of detectedreflectivity. Reflectivity as it relates to hazardous weather can be very complex.The role of radar is essentially to detect moisture in the atmosphere. Simplyput, certain types of weather reflect radar better than others. The intensity of aradar reflection is not necessarily an indication of the weather hazard level. Forinstance, wet hail returns a strong radar reflection, while dry hail does not. Bothwet and dry hail can be extremely hazardous.The different NEXRAD echo intensities are measured in decibels (dB) relativeto reflectivity (Z). NEXRAD measures the radar reflectivity ratio, or the energyreflected back to the radar receiver (designated by the letter Z). The value of Zincreases as the returned signal strength increases.
